#include <iostream>
#include <typeinfo>
#include <unistd.h>
#include <cassert>
class Any
{
public:
    Any() : _content(nullptr) {}

    template <typename T>
    Any(const T &val) : _content(new placeholder<T>(val)) {}
    Any(const Any &other)
        : _content(other._content ? (other._content->clone()) : nullptr)
    {
    }
    ~Any() { delete _content; }

    Any &swap(Any &other)
    {
        std::swap(_content, other._content);
        return *this;
    }

    template <typename T>
    T *get()
    {
        assert(typeid(T) == _content->type());
        return &((placeholder<T> *)_content)->_val;
    }

    template <typename T>
    Any &operator=(const T &val)
    {
        Any(val).swap(*this);
        return *this;
    }

    Any &operator=(const Any &other)
    {
        Any(other).swap(*this);
        return *this;
    }

private:
    class holder
    {
    public:
        virtual ~holder() {};
        virtual const std::type_info &type() = 0;
        virtual holder *clone() = 0;
    };

    template <typename T>
    class placeholder : public holder
    {
    public:
        placeholder(const T &val) : _val(val) {}
        const std::type_info &type() override
        {
            return typeid(T);
        }
        holder *clone() override
        {
            return new placeholder(_val);
        }

    public:
        T _val;
    };

    holder *_content;
};

class Test
{
public:
    Test() { std::cout << "构造" << std::endl; }
    Test(const Test &t) { std::cout << "拷贝" << std::endl; }
    ~Test() { std::cout << "析构" << std::endl; }
};
int main()
{

    // std::any a;
    // a = 10;
    // int *pi = std::any_cast<int>(&a);
    // std::cout << *pi << std::endl;

    // a = std::string("hello");
    // std::string *ps = std::any_cast<std::string>(&a);
    // std::cout << *ps << std::endl;

    Any a;
    {
        Test t;
        a = t;
    }

    a = 10;
    int *pa = a.get<int>();
    std::cout << *pa << std::endl;
    a = std::string("nihao");
    std::string *ps = a.get<std::string>();
    std::cout << *ps << std::endl;

    while (1)
        sleep(1);
    return 0;
}